Polyurethane compositions obtained by reacting a suitable prepolymer of an organic diisocyanate and a curing agent such as a polyalkylene glycol are generally well-known. Ordinarily, the organic diisocyanate is reacted with a suitable polyfunctional compound that contains active hydrogen groups to provide a prepolymer composition. The prepolymer is thereafter reacted with a suitable curing or cross-linking agent to provide the polyurethane composition. For instance, U.S. Pat. No. 3,362,921 discloses an elastomeric polyurethane derived from a prepolymer obtained by reacting castor oil and organic diisocyanate such as toluene diisocyanate. The resulting prepolymer is cross-linked by reaction with a suitable ester of a polyhydric alcohol which contains at least four hydroxy groups, e.g., pentaerythritol monoricinoleate. U.S. Pat. No. 3,362,921 discloses that it is essential to utilize a cross-linking or curing agent derived from esters of polyhydric alcohols that contain at least four hydroxy groups in order to obtain a cured polyurethane having desirable elastomeric properties for potting applications.